CameraTexture in Godot – Complete Guide

Cameras are integral to the fabric of modern gaming, providing a window to virtual worlds where stories, battles, and puzzles come to life. For anyone intrigued by the prospect of bringing reality into a game, CameraTexture in Godot 4 presents an exciting opportunity. This tutorial will delve into the CameraTexture class: a bridge that connects the real world with the digital one, allowing developers to integrate live camera feeds into their games and applications.

What is CameraTexture?

Exploring CameraTexture

CameraTexture is a class in Godot 4 that inherits from Texture2D and gives developers direct access to the texture data from a camera feed. This functionality is a cornerstone for augmented reality (AR) features, in-game photography, and other creative game mechanics that involve live visuals.

What is CameraTexture Used For?

The use of CameraTexture can range from simple tasks, like capturing player photos for in-game avatars, to more complex AR applications, where digital content is overlaid onto live feed images, blending reality with the game environment.

Why Should I Learn About CameraTexture?

Learning about CameraTexture not only sets the stage for crafting immersive game experiences but also opens up a realm of creative possibilities. By mastering its usage, developers can add another dimension to their skillset, staying on the cutting edge of game development technology.

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Setting Up a Basic Camera Feed

To start using CameraTexture in Godot 4, we first need to set up a basic feed that captures and displays the camera input onto a sprite within our game scene.

var camera_texture = CameraTexture.new()
var sprite = Sprite.new()

func _ready():
    camera_texture.open(0) # Opens the default camera
    sprite.texture = camera_texture
    add_child(sprite)

This code snippet creates a new CameraTexture object, a new Sprite, and sets the texture of the sprite to the live feed from the default camera (usually the first camera on the device).

Handling Camera Permissions

In mobile games or applications, we must handle permissions to use the camera. Godot has a simple API method for requesting camera permissions that can be implemented as shown below:

func _ready():
    if Engine.has_singleton("CameraServer"):
        var camera_server = Engine.get_singleton("CameraServer")
        camera_server.request_permissions()

This code checks if the CameraServer singleton is available and requests the necessary camera permissions from the user.

Adjusting Camera Feed Properties

Once the camera feed is being captured, you may want to adjust the properties, such as flipping the image or converting it to black and white. Here’s how you could flip the image horizontally:

func _ready():
    camera_texture.open(0)
    camera_texture.flip_h = true # Flips the camera feed horizontally
    sprite.texture = camera_texture
    add_child(sprite)

To modify the color to black and white, you’ll need to adjust the shader used by the sprite:

sprite.material = ShaderMaterial.new()
sprite.material.set_shader(shader) # Assume 'shader' is a reference to your black and white shader

Concatenating Multiple Camera Feeds

Godot’s CameraTexture can also handle multiple feeds. The following example demonstrates setting up two sprites with different camera feeds:

var camera_texture1 = CameraTexture.new()
var camera_texture2 = CameraTexture.new()
var sprite1 = Sprite.new()
var sprite2 = Sprite.new()

func _ready():
    camera_texture1.open(0) # Opens the default camera
    camera_texture2.open(1) # Opens the second camera, if available
    
    sprite1.texture = camera_texture1
    add_child(sprite1)
    
    sprite2.texture = camera_texture2
    sprite2.position = Vector2(400, 0) # Offsets the second sprite for visibility
    add_child(sprite2)

Each CameraTexture instance is assigned to a different Sprite, and we position the second sprite so both can be visible in the scene, assuming two cameras are accessible.

In the next part of the tutorial, we will explore how to manipulate the camera feed for more advanced scenarios, such as creating AR effects and integrating the CameraTexture class with other Godot nodes and systems.

Creating Augmented Reality (AR) effects involves overlaying digital content onto a live camera feed. Here’s a basic setup:

var camera_texture = CameraTexture.new()
var sprite = Sprite.new()
var ar_overlay = ARVRAnchor.new() # Your AR content node

func _ready():
    camera_texture.open(0)
    sprite.texture = camera_texture
    add_child(sprite)
    add_child(ar_overlay)

    # Position the AR overlay relative to the camera feed sprite
    ar_overlay.global_transform.origin = Vector3(0, 0, -10)

This sets up the groundwork for AR by adding an ARVRAnchor node to represent the position of our AR content in the 3D space relative to the camera’s perspective.

For a more dynamic application, you may want to capture the camera feed and update the texture in real-time. Here’s how:

func _process(delta):
    if camera_texture.is_active():
        sprite.texture = camera_texture.get_data() # Updates texture each frame

This ensures that any changes in the camera feed are reflected immediately in the game scene.

Applying effects to the camera feed can be done using shaders. Below is an example of how to invert the camera feed’s colors:

var invert_shader = ShaderMaterial.new()

func _ready():
    invert_shader.shader_code = """
        shader_type canvas_item;
        void fragment() {
            COLOR = vec4(1.0) - texture(TEXTURE, UV);
        }
    """
    sprite.material = invert_shader

This simple shader negates the colors of the texture, giving an inverted effect to the camera feed displayed on the sprite.

Interacting with the camera feed can be fascinating, like taking snapshots:

func take_snapshot():
    var image = camera_texture.get_data()
    image.flip_y() # Needed if the texture is inverted
    image.save_png("user://snapshot.png")

func _input(event):
    if event is InputEventMouseButton and event.pressed:
        take_snapshot()

The above function is called whenever a mouse button is pressed, capturing the current state of the camera feed and saving it as a PNG image.

To customize the CameraTexture resolution or frame rate, you might use the following:

func _ready():
    var camera_feed_id = camera_texture.set_feed_id(0)
    var camera_feed = CameraServer.get_feed(camera_feed_id)
    
    camera_feed.set_active(true)
    camera_feed.set_resolution(640, 480) # Set the resolution
    camera_feed.set_fps(30) # Set the frames per second

The code snippet above accesses a specific camera feed via its ID and modifies its properties, such as resolution and frames per second (FPS).

Incorporating user interaction, you can enable or disable the camera feed with a simple UI button:

func _on_Button_pressed(): # Assuming your button node is named "Button"
    if camera_texture.is_active():
        camera_texture.set_active(false)
    else:
        camera_texture.set_active(true)

This toggles the camera feed on and off each time the button is pressed.

Lastly, to ensure performance is maintained, always remember to close the camera feed when it’s no longer in use:

func _exit_tree():
    camera_texture.close()

Closing the camera feed when the node exits the tree helps to free up resources and is good practice for resource management.

As developers, we now have the tools to create interactive and visually compelling experiences by integrating the CameraTexture class within our Godot projects. Whether it’s for AR, social features, or innovative gameplay mechanics, the ability to manipulate and utilize camera feeds provides an extra layer of immersion that can significantly enhance the player experience.Incorporating CameraTexture into a 3D environment allows for inventive gameplay mechanics. For instance, you can project the camera feed onto a 3D object like a TV within the game:

var camera_texture = CameraTexture.new()
var mesh_instance = MeshInstance.new() # Assume there's a mesh that represents a TV

func _ready():
    camera_texture.open(0)
    mesh_instance.get_surface_material(0).albedo_texture = camera_texture
    add_child(mesh_instance)

Here, the mesh of the TV has its texture set to the live feed, creating an illusion that the game environment has a functional television.

Triggering actions in-game based on camera input can lead to interactive experiences. For instance, you could change the environment’s lighting based on the brightness of the camera feed:

var camera_texture = CameraTexture.new()
var environment = Environment.new() # Your game's environment
var light_threshold = 0.5

func _process(delta):
    var image = camera_texture.get_data()
    image.lock()
    var average_brightness = calculate_average_brightness(image)
    image.unlock()

    environment.adjust_brightness(average_brightness > light_threshold) # A hypothetical method to adjust environment brightness

func calculate_average_brightness(image):
    var total_brightness = 0.0
    for x in range(image.get_width()):
        for y in range(image.get_height()):
            var color = image.get_pixel(x, y)
            total_brightness += color.v  # 'v' is the value in HSV, represents brightness
    return total_brightness / (image.get_width() * image.get_height())

In this example, the average brightness of the camera feed is used to determine whether to adjust the in-game environment’s lighting.

Edge detection on a camera feed can create an outline effect or be used in gameplay mechanics. Below is an example of how to set up a shader for edge detection:

var edge_detection_shader = ShaderMaterial.new()

func _ready():
    edge_detection_shader.shader_code = """
        shader_type canvas_item;
        
        void fragment() {
            vec2 offsets[8] = vec2[](
            	vec2(-1, 1), // top-left
            	vec2(0, 1),  // top-center
            	vec2(1, 1),  // top-right
            	vec2(-1, 0), // center-left
            	vec2(1, 0),  // center-right
            	vec2(-1, -1), // bottom-left
            	vec2(0, -1),  // bottom-center
            	vec2(1, -1) // bottom-right
            );

            float kernel[9] = float[](
                -1, -1, -1,
                -1,  8, -1,
                -1, -1, -1
            );
            
            vec3 sample_tex[9];
            for (int i = 0; i < 9; i++) {
                vec2 offset = offsets[i % 8];
                sample_tex[i] = texture(TEXTURE, UV + offset / vec2(textureSize(TEXTURE, 0))).rgb;
            }

            vec3 col = vec3(0);
            
            for (int i = 0; i < 9; i++) {
            	col += sample_tex[i] * kernel[i];
            }
            
            float edge = length(col);
            COLOR = vec4(edge, edge, edge, 1.0);
        }
    """
    sprite.material = edge_detection_shader

This shader code applies an edge detection effect by sampling neighboring pixels and applying a kernel to highlight edges.

Managing camera zoom can create dynamic visual effects, as shown in the following code that simulates camera zoom:

func _input(event):
    if event is InputEventMouseButton:
        if event.button_index == BUTTON_WHEEL_UP:
            camera_texture.zoom += 0.1
        elif event.button_index == BUTTON_WHEEL_DOWN:
            camera_texture.zoom -= 0.1

This adjusts the camera zoom based on mouse wheel input, though the `CameraTexture` class does not natively support zoom, the concept can be applied to the camera node instead.

Lastly, integrating CameraTexture with physics can create unique interactions:

var camera_texture = CameraTexture.new()
var area_sprite = Area2D.new() # An Area2D that will react to the camera's feed

func _ready():
    camera_texture.open(0)
    sprite.texture = camera_texture
    add_child(area_sprite)

func _process(delta):
    var image = camera_texture.get_data()
    image.lock()
    if image.get_pixel(image.get_width()/2, image.get_height()/2).v > light_threshold:
        # Perform a physics action, perhaps triggering a RigidBody2D to move
        area_sprite.apply_central_impulse(Vector2(10, 0))
    image.unlock()

This code snippet checks the brightness of the camera’s central pixel and if it crosses the threshold, a physics impulse is applied to an object within the game’s physics system.

From these examples, it’s evident that CameraTexture is versatile across 2D, 3D, shaders, and interactive gameplay mechanics. The creative application of this class can lead to unique game experiences, embedded livestreaming features, or practical tools within the game engine. By harnessing the capabilities of CameraTexture, we can open doors to new realms of game design and player engagement.

Continue Your Game Development Journey

Your exploration of the CameraTexture class in Godot 4 is just the beginning of what you can achieve with this powerful game engine. Where to go next?

We encourage you to keep pushing the boundaries of your game development skills. For a structured learning path, consider our comprehensive Godot Game Development Mini-Degree. This collection of courses is designed to take you from beginner to professional, helping you build a robust portfolio of real Godot projects.

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Conclusion

As we’ve uncovered the depths of Godot’s CameraTexture class, it’s clear that the possibilities are only limited by our imagination. From AR experiences to in-game photography, the ability to mesh reality with the digital realm is an exhilarating prospect for any developer. By incorporating these techniques into your projects, you’re not just building games; you’re crafting experiences that resonate with players on a whole new level.

Remember, this is just one aspect of the vast landscape of game development. Continue your journey with Zenva’s Godot Game Development Mini-Degree and unlock the full potential of your creative vision. Let’s shape the future of interactive entertainment together, one line of code at a time!

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